Energy storage is considered as one of the key technologies for integrating large amounts of electricity produced from intermittent renewable sources. Adequate use of energy storage in the electric power system can lead to a reduction in system operating costs, while large storage capacity can affect electricity prices. In addition to the possibility of energy storage for subsequent use, there are many other services that make energy storage useful in market-oriented power systems, such as frequency regulation, voltage regulation, ensuring rotating and non-rotating reserves, peak shaving, black start, etc. Each purpose has special requirements for response time, the amount of required energy, etc. All energy storage technologies, which differ substantially in their characteristics, are not suitable for all purposes. Therefore, existing and some new technologies for energy storage are intensively researched and improved. A large increase in energy storage capacities is expected.

However, all energy storage technologies for power applications require large initial investments, energy losses occur at each charge and discharge cycle, maintenance is required, etc. The optimal requirements for energy storage depend on the characteristics of the power system (mainly on the characteristics of power plants as well as the share and characteristics of renewable sources), on the variation in the prices of electricity and auxiliary services on the energy exchanges, the possibilities of energy storage, etc.

In accordance with above, questions arise about the purpose of energy storage, the required characteristics of energy storage, adequate storage capacities, influencing parameters, etc. the influence of the power system structure on the characteristics of energy storage is of particular interest.